To delineate potential discreet subgroups of patients with schizophrenia we have studied quantifiable psychopathological, behavioral, and physiological variables in schizophrenic patients. In terms of psychopathology we have done two studies: (1) Constructed a quotient of two item scores from the BPRS as follows: suspiciousness/(disorganized speech + suspiciousness) x 100. Patients with paranoid schizophrenia had a higher quotient score (70) than other patients with schizophrenia (47, p less than .002). (2) To examine whether psychopathology may be related to the expression of TD in schizophrenia we examined BPRS syndrome clusters in patients with schizophrenia. Patients with TD had a preponderance of high depression and negative symptoms scores but lower anxiety scores. Behaviorally we are concentrating on the issue of aggression in schizophrenia and have found that patients with schizophrenia are more aggressive than are other research patients (greater than 40% committed physical assaults on others) and that assaultiveness tended to be associated with reduced cerebrospinal fluid (CSF), norepinephrine (NE), and MHPG. A final physiological variable we have studied is urine volume. The mean volume of urine of patients with schizophrenia is twice that of normal controls (2300 vs 1300 ml/24hr).